Interleaved FDMA-a new spread-spectrum multiple-access scheme

A new spread-spectrum multiple-access scheme applicable for both the uplink and the downlink of a mobile radio communications system is proposed, which is termed “interleaved frequency-division multiple-access”. This scheme combines the advantages of spread-spectrum and multicarrier transmission. Moreover, it can be viewed as a special kind of a multicarrier spread-spectrum scheme where user discrimination is carried out using frequency-division multiple-access. The multiple-access capability is achieved by assigning to each user a different set of orthogonal subcarriers. The orthogonality between the different users is maintained at the receiver, even in time-dispersive channels resulting in no multiple-access interference. However, the cost to avoid multiple-access interference is to allow for intersymbol interference and therefore equalization is required at the receiver